Subtitle like text always facing to the camera
Setup a new Scene for text.
Select the Camera and change it to Orthographic.

Properties > Data(Camera icon) > Lens > Orthographic





Reset Camera Location (Alt+G) and Rotation
(Alt+R).
Move Camera along Z-axis till it is above 0.
Text Object can be place on the X-Y plan as you like.




To combine the animation and text, crate another new Scene and import the 2 Scenes into VSE.